The invention is related to a primary actuator assembly for fluid valves such as those used in sprinkler or irrigation systems. More particularly, existing fluid valves known as "three-way" primary actuated diaphragm valves, such as those manufactured by Buckner, Inc., use a solenoid actuation assembly that causes the high pressure water from the high pressure side of the valve to close the valve and the difference between atmospheric pressure or valve outlet pressure and the inlet pressure to open the valve. In a typical arrangement, there is an opening in the high pressure side of the fluid line which is connected to a solenoid inlet valve. When the solenoid is in the de-energized position, the solenoid inlet valve is open and allows high pressure water to pass through the solenoid inlet valve and enter a solenoid chamber that is connected to a diaphragm chamber in the fluid valve. Thus connected, the diaphragm chamber is at the same pressure as the high pressure side of the fluid line. The area of the diaphragm presented to the diaphragm chamber is larger than the main seal seat area presented to the high pressure side of the closed valve. This difference in area creates a pressure bias force, which, in conjunction with a bias force from a spring in the diaphragm chamber, act to hold the diaphragm in the closed position and keep the valve closed.
To open the fluid valve, the solenoid is activated which closes the solenoid inlet valve and opens a solenoid outlet valve. The solenoid outlet valve is connected by a channel running through the center of the solenoid to the diaphragm chamber of the fluid valve. This reduces the pressure in the diaphragm chamber to atmospheric pressure. The pressure imbalance between the diaphragm chamber and the high pressure side of the valve causes the valve to open and remain open as long as the solenoid is energized. In typical valves manufactured by Buckner, Inc. for example, it takes approximately 8 watts of power to energize the solenoid and keep it open. The energized solenoid produces approximately 1.27 pounds of force, in addition to the force necessary to overcome the solenoid return spring, to close the solenoid inlet valve and open the outlet valve against as much as 200 psi of water pressure (assuming solenoid valve orifice diameters of 0.090"). When the solenoid is de-energized, a solenoid spring causes a solenoid plunger to reverse direction and open the solenoid inlet valve and close the solenoid outlet valve. This causes, as previously described, the diaphragm chamber to be connected to the high pressure side of the fluid line which in turn causes the fluid valve to close. The size of the holes of the solenoid inlet and outlet valves are typically approximately 0.090 inches in diameter. These holes are large enough to cause sufficient flow between the high pressure side of the valve and the diaphragm chamber and are large enough so that the solenoid valves are not easily obstructed by contaminants or debris in the fluid line. The power for operating the solenoid is typically supplied by a valve control unit which is in turn connected to a standard power source such as 110 volt AC. The relatively large amount of power required to operate the solenoids, especially in a system with numerous valves, virtually requires that the control unit be connected to a constant source of power such as power provided by a utility company as opposed to connecting to battery power or solar power. This increases the installation expense due to the cost of running the power lines to the control unit. This expense is even higher when the control unit is located in a remote area.
A need therefore exists for an electronically actuated fluid valve that consumes a very low amount of power when the valve is being opened or closed, that does not require utility company power, and that does not consume any power when the valve is in the opened or closed position.